Question: What is the portion of the Nile from the country they migrate to the country where University of Khartoum is located called?
Context: Document 1: University of Khartoum: It features several institutes, academic units and research centers including Mycetoma Research Center, Soba University Hospital, Saad Abualila Hospital, Dr. Salma Dialysis centre, Institute of Endemic Diseases, Institute for Studies and Promotion of Animal Exports, Institute of African and Asian Studies, Institute of Prof. Abdalla ElTayeb for Arabic Language, Development Studies and Research Institute and U of K publishing house. The Sudan Library, a section of the university's library, serves as the national library of Sudan.
Document 2: Black people: About 150,000 East African and black people live in Israel, amounting to just over 2% of the nation's population. The vast majority of these, some 120,000, are Beta Israel, most of whom are recent immigrants who came during the 1980s and 1990s from Ethiopia. In addition, Israel is home to over 5,000 members of the African Hebrew Israelites of Jerusalem movement that are descendants of African Americans who emigrated to Israel in the 20th century, and who reside mainly in a distinct neighborhood in the Negev town of Dimona. Unknown numbers of black converts to Judaism reside in Israel, most of them converts from the United Kingdom, Canada, and the United States.
Document 3: Nile: The Nile (Arabic: النيل‎, written as al-Nīl; pronounced as an-Nīl) is a major north-flowing river in northeastern Africa, and is the longest river in Africa and the disputed longest river in the world (Brazilian government claims that the Amazon River is longer than the Nile). The Nile, which is about 6,650 km (4,130 mi) long, is an "international" river as its drainage basin covers eleven countries, namely, Tanzania, Uganda, Rwanda, Burundi, the Democratic Republic of the Congo, Kenya, Ethiopia, Eritrea, South Sudan, Republic of the Sudan and Egypt. In particular, the Nile is the primary water source of Egypt and Sudan.The river Nile has two major tributaries, the White Nile and Blue Nile. The White Nile is considered to be the headwaters and primary stream of the Nile itself. The Blue Nile, however, is the source of most of the water and silt. The White Nile is longer and rises in the Great Lakes region of central Africa, with the most distant source still undetermined but located in either Rwanda or Burundi. It flows north through Tanzania, Lake Victoria, Uganda and South Sudan.  The Blue Nile begins at Lake Tana in Ethiopia and flows into Sudan from the southeast. The two rivers meet just north of the Sudanese capital of Khartoum.The northern section of the river flows north almost entirely through the Sudanese desert to Egypt, then ends in a large delta and flows into the Mediterranean Sea. Egyptian civilization and Sudanese kingdoms have depended on the river since ancient times. Most of the population and cities of Egypt lie along those parts of the Nile valley north of Aswan, and nearly all the cultural and historical sites of Ancient Egypt are found along river banks.
Answer: Blue Nile
Reasoning steps: Where did they migrate from? Answer: Ethiopia.
University of Khartoum >> country Answer: Sudan
Which portion of the Nile runs from Ethiopia. to #2 ? Answer: Blue Nile